Closure plugs

ABSTRACT

A washerless closure plug for closing althreaded opening in the block of automotive engines includes an externally threaded nipple surrounded by a sharp shoulder, which shoulder is provided with a pair of forwardly facing ribs. When the nipple is screwed into an engine block the ribs form a seal with the block wall to resist leakage from the block and to damp the transmission of vibrational forces from the block to the closure plug which tend to unscrew the closure plug from the block.

RELATED APPLICATIONS

This invention is a continuation of application Ser. No. 08/547,474,filed on Nov. 24, 1995, titled Washerless Block Heater, now U.S. Pat.No. 5,553,578.

BACKGROUND OF THE INVENTION

This invention relates to closure plugs of a type that are retained in athreaded bore passing through the wall of the engine block which mayconnect into the water jacket of the block. Such closure plugs include athreaded nipple, an outwardly facing end portion having a diametricdimension greater than that of the nipple, and a sharp shoulderconnecting the nipple and the end portion. In the prior art, a washer isdisposed on the nipple for compression between the shoulder and the wallof the engine block surrounding the bore. The washer provides a sealingfunction to prevent the escape of engine coolant from the block, and adamping function, to reduce the transmission of vibration between theengine block and the closure plug closure plug which tends to loosen theseal across the interface.

The reliance upon a sealing washer is generally found to increase theinstallation time of the closure plug. In addition, the inadvertent lossof the sealing washer in the installation process can engenderconsiderably increased costs to rectify the deficiency when it becomesapparent. Although it is well known to capture washers on screwedmembers, this tends to increase assembly costs of small assembly runitems such as block closure plugs.

It is an object of my invention to provide washerless closure plugs forautomotive engines.

It is another object of my invention to provide closure plugs forautomotive engines that are more easily assembled into the automotiveengine, with reduced margins for error.

BRIEF SUMMARY OF THE INVENTION

In accordance with one aspect of my invention, a closure plug for anautomotive engine includes a body of a hard malleable metal comprisingan externally threaded nipple portion, an outer end portion having adiametric dimension greater than that of the nipple portion, and a sharpshoulder portion connecting the nipple portion and the end potion. Firstand second spaced apart ribs are raised on the shoulder portionconcentric with the nipple portion. The nipple portion is received in athreaded bore in a wall of the block of an automotive engine to compressthe ribs against the wall and form a damping seal therewith.

Typically, the preferred hard malleable metal from which the body of theclosure plug is formed will be brass, but other metals includingaluminum may also be utilized.

Suitably the sealing ribs have a generally semi-circular profile eachhaving a small diameter, typically of about 1 mm, whereby whencompressed against the engine closure plug, the ribs will undergo apredominantly plastic deformation without scoring of the engine blockwall against which the closure plug body seals.

The foregoing objects and aspects of the invention, together with otherobjects, aspects and advantages thereof will be more apparent from aconsideration of the following description of the preferred embodimentthereof taken in conjunction with the drawings annexed hereto.

IN THE DRAWINGS

FIG. 1 shows a closure plug in accordance with the invention in frontperspective view;

FIG. 2 is a fragmentary cross-section on line 2--2 of FIG. 1; and

FIG. 3 is similar to FIG. 2 but shows the closure plug mounted in afragmentary portion of an automotive engine block.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings in detail, an automotive engine closure plugin accordance with the invention is identified generally therein by thenumeral 10. Closure plug comprises a body 12 suitably formed from forgedbrass, and includes a nipple portion 14, an outwardly facing end portion16 suitably having hexagonal cross section, which end portion hasdiametric dimension greater than that of nipple portion 14. A sharpshoulder portion 20 interconnects nipple portion 14 and end portion 16.Nipple portion 14 has external threads 22 along the length thereof. Ahairpin immersion heater (not shown) may optionally be sealed to nippleportion 14 to project forwardly therefrom where the closure plug forms apart of an engine block heater.

As thus far described, closure plug 10 is of a wholly conventionalnature, and in use a sealing washer would be employed therewith. Thesealing washer is obviated in accordance with my invention by providingshoulder portion 20 with a pair of forwardly projecting ribs 30, 32concentric with nipple portion 14.

Closure plug 10 is received in the threaded bore B of an engine block E,which block is defined in part by an outwardly facing wall W surroundingthe bore B. A torque force applied to the closure plug 10 compresses theribs 30, 32 against wall W.

Sealing ribs 30, 32 will suitably be generally semicircular in crosssection, suitably having a diameter of approximately 1 mm, so as undergoprimarily a plastic deformation when compressed against the wall W.While the spacing between ribs 30, 32 is not critical, the ribs will bepositioned on shoulder potion 20 in a manner to maximize the spacingtherebetween, commensurate with the ribs being adequately spaced fromthe margins of shoulder 20. While I do not wish to be bound by theory,it appears that the different diameters on which the rib 30, 32 areformed has a dampening effect on the transmission of vibration betweenengine block E and closure plug 10.

It will be apparent that many changes may be made to the illustrativeembodiment while falling within the scope of the invention, and it isintended that all such changes be covered by the claims appended hereto.

I claim:
 1. A closure plug for an automotive engine, said closure plugincluding a body of a hard malleable metal including an externallythreaded nipple portion, an outer end portion having a diametricdimension greater than that of said nipple portion, and a sharp shoulderportion connecting said nipple portion and said end portion;first andsecond spaced apart ribs raised on said shoulder portion concentric withsaid nipple portion; said nipple portion being receivable in a threadedbore in a wall of the block of an automotive engine to compress saidribs against said wall and form a damping seal therewith.
 2. A closureplug as defined in claim 1 wherein said hard malleable metal is brass.3. A closure plug as defined in claim 1 wherein said sealing ribs eachhave a generally semi-circular cross section.
 4. In combination, anautomotive engine including an engine block having a passage therein fora heat exchange liquid coolant within said block; said block having athreaded bore therethrough in connection with said passage and anoutwardly facing surface surrounding said bore;a closure plug for saidbore including a body formed of a hard malleable material including anexternally threaded nipple portion matable with said threaded bore andan outer end portion having a diametric dimension greater than that ofsaid nipple portion with a sharp shoulder therebetween; a first andsecond spaced apart ribs raised on said sharp shoulder concentred withsaid nipple; said spaced apart ribs mating with said outwardly facingsurface of said block to form a damping seal therebetween.
 5. Thecombination of claim 4 wherein said hard malleable material is brass. 6.The combination of claim 4 wherein said sealing ribs each have agenerally semi-circular cross section.